In the steam turbine art, there may be a single rotor with peripheral vanes against which the steam, entering the housing in a tangential direction, is directed. Where there are a plurality of rotors, they are customarily secured in spaced relation along a common shaft with stationary steam reversing blades therebetween. The steam is thus directed successively to all of the rotors to make maximum use of the available energy.
As far as I am aware, the prior art does not disclose the practice of directing steam from two nozzles simultaneously at two side by side or overlapping rotors mounted on a common shaft within a housing where one rotor is keyed to the shaft and the other rotor is free to rotate on the shaft.